Salmon Study: What Does it Take to Survive a Warming River?

Sockeye salmon are one of many species of wildlife who will need to adapt to warming water temperatures caused by climate change… or die.

A new study published this week in the journal Science examines sockeye salmon populations in the Fraser River of British Columbia. The Fraser River has heated up by about 3.5 degrees Fahrenheit since the 1950s. Salmon mortalities can be close to 95% of millions in population during the river’s warmest years.

There are some sockeye salmon who will go to great lengths to survive. Some salmon will travel almost 680 miles upstream with an elevation gain of 3,000 feet to find colder, glacial waters.

Deemed “superfish” by researchers these fish may have what it takes to survive a warming river.

Photograph courtesy of Robert Polo, Science/AAAS

Will salmon populations simply evolve to become “superfish” to survive climate change?

Researchers in the study tested these “superfish” and others by placing them in swim treadmills and monitoring their vital signs while adjusting water temperatures. The “superfish” have larger hearts that allow them to move great distances to escape temperatures as they warm. Some “less super” fish can only handle water temperatures of about 62 degrees Fahrenheit before they reach a point of cardiovascular collapse and just cannot make the trip. It is unknown at this time why some fish develop larger hearts and others do not.

There are other limits to “superfish” travels. While some can travel 600 miles, others may only make it 400 miles, making it more difficult to spawn. Also salmon might not have the option to swim north or higher in altitude in cases of natural habitat limits, pollution, habitat destruction or ever-climbing temperatures.

To assist wildlife survival in a changing climate conservation managers are looking into options such as restoring or expanding natural areas, planting shady vegetation to cool river temperatures and, in some cases, potentially moving species to cooler locations.

What can you do to help the millions of fish in warming waters? Right now, critical salmon conservation funding and the Environmental Protection Agency’s ability to limit carbon pollution are both under attack. Speak up for salmon!

Learn more about National Wildlife Federation’s efforts to help wildlife survive warming temperatures and other impacts of climate change.